jquery

初始化一个函数

function jQuery(selector) {   
return new jQuery.fn.init(selector);  }

手写each函数

 each(callback) {
      for (var i = 0; i < this.length; i++) {
        callback(this[i]);
      }
      return this;
    },

手写显示与隐藏

 toggle() {
      this.each(function (item) {
        if (item.style.display != "none") {
          item.style.display = "none";
        } else {
          item.style.display = "block";
        }
      });
    },

定义构造函数显示原型

jQuery.fn =jQuery.prototype = {
		constructor:jQuery,
		jquery:"9.0.0",
		length:0,
		get(index){
			return this[index];
		},

全局访问

window.$ = window.jQuery = jQuery;

extend方法

jQuery.extend = jQuery.fn.extend = function () {
    var options, name, src, copy, copyIsArray, clone,
      target = arguments[0] || {},
      i = 1,
      length = arguments.length,
      deep = false;
    if (typeof target === "boolean") {
      deep = target;
      target = arguments[i] || {};
      i++;
    }
    if (typeof target !== "object" && !isFunction(target)) {
      target = {};
    }
    if (i === length) {
      target = this;
      i--;
    }
    for (; i < length; i++) {
      if ((options = arguments[i]) != null) {
        for (name in options) {
          src = target[name];
          copy = options[name];
          if (target === copy) {
            continue;
          }
          if (deep && copy && (jQuery.isPlainObject(copy) ||
            (copyIsArray = Array.isArray(copy)))) {
            if (copyIsArray) {
              copyIsArray = false;
              clone = src && Array.isArray(src) ? src : [];
            } else {
              clone = src && jQuery.isPlainObject(src) ? src : {};
            }
            target[name] = jQuery.extend(deep, clone, copy);
          } else if (copy !== undefined) {
            target[name] = copy;
          }
        }
      }
    }
    return target;
  }